Openstreetmap recursive street extraction algorithm

OpenStreetMap is an open source map containing geographical information. Three key elements make up the map data for OpenStreetMap namely nodes, ways and relations. An OpenStreetMap API allows the retrieval of information about streets and nodes. The developed application extracts all the streets from within a specific bounding box. In this paper three possible algorithms to extract the streets are discussed with their advantages and disadvantages. A recursive algorithm is considered the most appropriate given the requirements of the application. The recursive algorithm exploits the functionalities in OpenStreetMap API to extract all the streets in a specific bounding box. Starting from the initial node streets are added recursively until all the streets with at least one node within the bounding box are extracted. Streets are broken up into links and rearranged in a way to allow their reuse by other applications. The recursive algorithm is explained in detail describing the flow of execution and the used methods. A concrete example illustrates step by step the execution of the application and the resulting RDF output is shown to demonstrate the results. The application successfully extracts the required data and outputs it as required. Few suggestions are given in order to improve the application and to add more functionalities to it.